Albert Edward Stroemer appeals his convictions and consecutive 99-year sentences for two sexual batteries and four robberies and the trial court’s retention of jurisdiction over the first third of each sentence pursuant to section 947.16, Florida Statutes (1978). We reverse the retention of jurisdiction, but otherwise affirm.

Because the offenses in question were committed on March 31, 1977, and section 947.16 did not become effective until June 19, 1978, the application of the statute to appellant’s sentences was ex post facto and therefore violative of his constitutional rights. State v. Williams, 397 So.2d 663 (Fla. 1981); Rodriguez v. State, 380 So.2d 1123 (Fla. 2d DCA 1980).

We find no merit to the other points raised by appellant.

Accordingly, the trial court’s order retaining jurisdiction for the first third of appellant’s sentences is vacated. The cause is remanded for correction of the Uniform Commitments to Custody of the Department of Corrections. The judgments and sentences, since they made no reference to retention of jurisdiction, are affirmed as rendered.